International Patent application W02008/054194 discloses a method for conditionally routing a call made to a fixed telephone number. The call is possibly routed to one or more mobile terminal via an IP network if a mobile terminal is within reach of an access point in the IP network. Alternatively the call is routed to an alternative terminating point, such as an answering machine, using a list stored in a network node implementing the routing service.
International Patent application W02008/054218 relates to a method of routing a call made by a calling party to a fixed telephone number.
German Patent DBI 9731461 recites a tariff charging method for calls from mobile subscribers in a radio network.